Implantable medical devices may be used to deliver electrical stimulation therapy to patients to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson's disease, epilepsy, urinary or fecal incontinence, sexual dysfunction, obesity, or gastroparesis. An implantable medical device may deliver electrical stimulation therapy via leads that include electrodes, which may, for example, be located proximate to the spinal cord, pelvic nerves, stomach, or within the brain of a patient. In general, implantable medical devices deliver electrical stimulation therapy in the form of electrical pulses or substantially continuous-time signals.
A clinician may select values for a number of programmable parameters in order to define the electrical stimulation therapy to be delivered to a patient. For example, in the case of stimulation delivered in the form of electrical pulses, the clinician may select an amplitude, which may be a current or voltage amplitude, and pulse width for a stimulation waveform to be delivered to the patient, as well as a rate at which the pulses are to be delivered to the patient. The clinician may also select particular electrodes within an electrode set to be used to deliver the pulses and the polarities of the selected electrodes. A selection of electrodes from among those available on one or more leads and their polarities may be referred to as an electrode configuration. A group of parameter values, which may include an electrode configuration, may be referred to as a program in the sense that they drive the electrical stimulation therapy to be delivered to the patient.
The process of selecting values for the parameters can be time consuming, and may require a great deal of trial and error before a desirable program is discovered. The “best” program may be a program that best balances greater clinical efficacy and minimal side effects experienced by the patient. In addition, power consumption by a medical device may be different during delivery of therapy according to different programs.
The clinician typically needs to test a large number of possible electrode configurations in order to identify one or more desirable electrode configurations. As a portion of the overall parameter selection process, the process of selecting electrodes and the polarities of the electrodes, i.e., electrode configurations, can be particularly time-consuming and tedious. In some cases, the clinician may test electrode configurations by manually specifying each configuration based on intuition or some idiosyncratic methodology. The clinician may then record notes on the efficacy and side effects of each configuration after delivery of stimulation via that configuration. In this manner, the clinician is able to later compare and select from the tested configurations. As an example of the magnitude of the task, an implantable electrical stimulator commonly delivers spinal cord stimulation (SCS) therapy to a patient via two leads that include eight electrodes per lead, which equates to over 43 million potential electrode configurations.
In order to improve the efficacy of electrical stimulation therapy, implantable medical devices have grown in capability and complexity. Modern implantable medical devices tend to have larger numbers of potential electrode configurations, larger ranges for other parameters, and the ability to substantially simultaneously deliver multiple therapy programs by interleaving stimulation pulses in time. Although these factors increase the clinician's ability to tailor therapy for a particular patient or disease state, the burden involved in optimizing device parameters has similarly increased.